A young man cradles his M1 rifle as he stands shoulder to shoulder with other young men in one of thousands of landing craft that bob up and down as they make their way through the choppy waters of the English Channel toward the French coastline.

Artillery shells whiz by, exploding all around them while machine gun fire rains down from the cliffs overlooking the beach. The signal is finally given, the landing craft’s ramp lowers into the water and that young man and his comrades throw themselves waist deep into the water and make their way past mines, barbed wire and other obstacles, braving enemy fire as they look to establish a foothold on the beaches of Normandy.

There’s no way for us today to truly understand the terror and fear experienced in that moment. And there’s also no way to fully appreciate the sacrifice that these men made on that fateful day. If they hadn’t, there’s no telling how World War II might have ended, or what would have come after that.

Eighty years a...